1. Field of Invention
The invention relates to new indolestyryl compounds and, in particular, to new indolestyryl compounds and their uses in high-density optical recording media.
2. Related Art
With the coming of information and multimedia era, computer, communication and consumer electronics have higher demands for larger storage density and capacity. Due to the large amount of information exchange, it is desirable to develop a high-density, small and cheap storage medium. Conventional magnetic storage media are already insufficient for current uses; high-density optical information storage media are the main subject under study. There had been some proposed principles and methods for increasing the storage density in optical information storage media. Some of them are important and have already been successfully implemented. One method is to shorten the wavelength of the laser beam. For example, red lasers are replaced by blue lasers. One can also achieve the same goal by increasing the NA (Numerical Aperture) of the lens. Another method is to improve the digital signal coding means or to utilize optical disk recording with the so-called ultra-high resolution near-field optical structure. These methods can all effectively increase the storage density.
On the other hand, another research field of optical information storage media is to replace the organic dyes used in optical recording layers by those with better optical properties. In recent years, one-time recording compact discs (CD-R) have become people""s favorite storage media due to their cheap prices, fast burning speeds, convenience in carriage, and high compatibility among different personal computers. To achieve high-density storage, dyes for such media as one-time recording digital versatile discs (DVD-R) with 4.7 GB capacity have become an important subject under research. Since the laser for high-density storage media such as DVD-R""s has a light wavelength of 650 nm, which is different from that of the laser for CD-R""s (780 nm), the dyes cannot be shared between the two kinds of media. This is why developing new organic dyes for high-density storage media is an urgent need.
It is an objective of the invention to provide new indolestyryl compounds and their uses in high-density recordable optical discs. Such indolestyryl compounds have a maximum absorption for light wavelengths in the range of 500 nanometers to 700 nanometers (xcex=500 nmxcx9c700 nm). The indolestyryl compounds also have high sensitivity, chemical stability toward light and heat and good solubility for organic solutions.
To achieve the above objective, the invention provides new indolestyryl compounds which have the following graphical chemical structure (I). 
As shown in the structure (I), R1, R2, R3, R4, R5 and Yxe2x88x92 represent groups connected to different positions on the chemical structure. In particular, when R1 is CH2C6H4CO2R6, (CH2)nSO3R7, or (CH2)nCO2R7, Yxe2x88x92 can be any anions such as (TCNQxe2x88x92)n (teteacyano-p-quinodimethane) and (TCNExe2x88x92)n (tetracyanoetylene)(n=0, 1), CIO4xe2x88x92, SbF6xe2x88x92, PF6xe2x88x92, BF4xe2x88x92, and halide ions (Xxe2x88x92) etc. R2 and R3 are same or different groups selected from hydrogen atoms, alkyl groups with one to eight carbons (C1-8), alkyl-oxygen groups with one to eight carbons (C1-8) and alkyl-ester groups one to eight carbons (xe2x80x94CO2R8). R2 and R3 can be connected to form a pyrrolidine ring, R2 and R3 can be connected to benzene ring to form a julolidine ring. R4 and R5 are same or different groups selected from hydrogen atoms, alkyl groups with one to eight carbons (C1-8), trifluoromethyl groups, alkyl-oxygen group, carboxyl groups, nitric groups, amide groups (CONR9R10), sulfonic groups, SO3R11, alkyl-ester groups with one to eight carbons (C1-8), and halide ions (Xxe2x88x92).
When the choice of Yxe2x88x92 needs to match R1 and R1 is an alkyl group with one to eight carbons (C1-8), Yxe2x88x92 must be one of TCNQxe2x88x92 (teteacyano-p-quinodimethane) and TCNExe2x88x92 (tetracyanoetylene). Moreover, when R1 is one of CH2C6H4CO2R6, (CH2)nSO3R7, and (CH2)nCO2R7, Yxe2x88x92 can be one of TCNQxe2x88x92 (teteacyano-p-quinodimethane), TCNExe2x88x92 (tetracyanoethylene), CIO4xe2x88x92, SbF6xe2x88x92, PF6xe2x88x92, BF4 and halide ions.
When R1 of the new indolestyryl compound is CH2C6H4CO2R6, (CH2)nSO3R7, or (CH2)nCO2R7, R6 and R7 can be an alkyl group with one to eight carbons or alkyl fluoride (C2F4, CF3 etc.).
When R4 and R5 in the new indolestyryl compound is an alkyl-ester group (xe2x80x94CO2R8) with one to eight carbons (C1-8), R8 can be an alkyl group with one to eight carbons or alkyl fluoride (C2F4, CF3). If R4 and R5 are amide groups (xe2x80x94CONR9R10), R9 and R10 may be same or different groups. R9 and R10 can be hydrogen atoms or alkyl groups with one to six carbons. When R4 and R5 are xe2x80x94SO3R11 groups, R11 may be hydrogen atoms or alkyl groups with one to six carbons. The above choices of groups can be selectively applied to the chemical formula (I).
Furthermore, the manufacturing method of the new indolestyryl compounds requires the reaction between the compound (II) and the compound (III) in an organic solution. The manufacturing method of the new indolestyryl compounds is explicitly as follows:
Mix the compound (II) and the compound (III) in an organic solution. They undergo a reaction to obtain an indolestyryl compound (IV) with halide ions (Xxe2x88x92). 
Finally, as shown in the following reaction formula, the indolestyryl compound (IV) with halide ions and one of the lithium, sodium and potassium salt (LiY, NaY, KY) are mixed in an organic solution to exchange ions, obtaining a new chemical compound with the chemical formula (I). 
The disclosed indolestyryl compounds can be directly applied to usual DVD""s and the recording layers of other high-density data storage media.
It is another objective of the invention to provide a high-density data storage medium using the new indolestyryl compound dyes in its recording layer. Since this kind of indolestyryl compounds can be easily synthesized and purified, they are cheaper than other usual dyes. In addition, the high-density data storage media using the disclosed indolestyryl compounds have good light sensitivity and superior chemical stability in the recording layer.
It is yet another objective of the invention to use the new indolestyryl compounds as the recording layer of a recordable optical disc to form a high-density optical recording medium. The recordable optical disc comprises: a first substrate, which is a transparent substrate with grooves, a recording layer, which is formed on the first substrate surface using the new indolestyryl compounds, a reflective layer formed on the recording layer, a second substrate, which is a transparent substrate with grooves connected to the reflective layer with an attachment layer. One feature of the invention is that the new indolestyryl compounds are used as dyes in the recording layer.